Information message about the strong earthquake at the north of Mozambique on February 22, 2006 |
| The earthquake with magnitude M=7.3 has happened on February 22 at 22:19 GMT (February 23 at 1:19 A.M. Moscow time) in Mozambique. Epicenter of this earthquake was at 220 km to the South-West from the main port city of Mozambique - Beira. It was felt in Zimbabwe, Botswana, Zambia and SAR. From ITAR-TASS information two persons were killed and 13 injured. |
| Parameters of the earthquake
have been determined in the Alert Service (AS) of Information
Processing Center (IPC) of Geophysical Survey of RAS in Obninsk with station data
obtained from digital and analog seismic stations of Russia, countries of CIS
and from abroad. Alert message on this earthquake has been delivered in 40 min after
registration to the Ministry of Emergency of the Russian Federation (EMERCOM). |
| Preliminary processing has been done with data from 29 stations, accurate processing - with data 39 stations. |
| Fig. 1 presents fragments of records obtained from digital stations: Diego Garcia (39.8 degrees), Sanae (54.8 degrees), Apeirantos (58.3 degrees), Isparta (58.6 degrees), Garni (61.5 degrees), Kasperske Hory (72.1 degrees). Fig. 2 presents fragments of records obtained from digital stations: Ala-Archa (73.7 degrees), Obninsk (75.9 degrees), Vasula (79.4 градуса), Borovoe (80.3 degrees), Kurchatov (81.7 degrees), Kongberg (82.8 degrees). |
Figure 1
| 
Figure 2
|
|
| IPC GS RAS also has obtained information with parameters of this event from some seismological centers, these data are given in table 1: |
| Table 1 |
| NN |
Time in origin h-min-s (GMT) |
Lat degr. |
Lon degr. |
Depth km |
N s/st |
Ms/ N |
mb/ N |
I0 calc |
GAP |
Center | | 1 |
22-19-07.2 |
-21.04 |
33.66 |
10 |
39 |
7.3/15 | 6.7/11 | 10-10.5 | 81 | IPC GS RAS (Accurate) | | 2 |
22-19-11.4 |
-20.84 |
33.58 |
33 |
29 |
7.3/11 | 6.7/6 | 8.5-9 | 81 | IPC GS RAS (Preliminary) | | 3 |
22-19-06.6 |
-21.29 |
33.44 |
10 |
261 |
7.5Mw | | | 40 | CSEM | | 4 |
22-19-08.7 |
-21.22 |
33.34 |
10 |
163 |
7.3/6 | 6.5/40 | | | NEIC (Preliminary) | | 5 |
22-19-07.6 |
-21.21 |
33.43 |
11 |
169 |
7.5/137 | 6.5/63 | | 25 | NEIC (Accurate) | |
| IPC GS RAS - Informational Processing Center, Geophysical Survey, Russian Academy of Sciences |
| CSEM - European - Mediterranean seismological center |
| NEIC - National Earthquakes Information Center of US Geological Service |
| Epicenter |
| Epicenter of this earthquake was located at 220 km to the south-west from the main port city of Mozambique - Beira and at 530 km to the north from Mozambique capital Maputo. |
| Aftershock |
| This earthquake was accompanied with aftershocks. The strongest of them have been registered by Geophysical Survey of RAS. |
| N |
Date & Time (GMT)
yy-mm-dd hh:mm:sec |
Lat
degr. |
Lon
degr. |
Depth
km |
N
station |
Ms/ N |
mb/ N |
Io
calc. |
Region |
| 20060461 | 2006-02-23 01:18:03.0 | -20.96 | 33.9 | 33 | 12 | - | 4.9/ 4 | 3-3.5 | Mozambique | | 20060462 | 2006-02-23 01:23:41.0 | -21.68 | 33.21 | 33 | 22 | - | 5.3/ 4 | 4-4.5 | Mozambique | | 20060463 | 2006-02-23 02:22:09.0 | -21.33 | 33.52 | 33 | 17 | - | 5.5/ 4 | 4.5-5 | Mozambique | | 20060470 | 2006-02-23 21:32:12.0 | -20.64 | 33.91 | 33 | 11 | - | 5.2/ 5 | 4-4.5 | Mozambique | | 20060476 | 2006-02-24 23:24:42.0 | -21.27 | 33.47 | 33 | 10 | 4.1/ 3 | 5.0/ 5 | 3.5-4 | Mozambique | |
| Macroseismic manifestations |
| Two people were killed and 13 injured as a result of this earthquake. It was felt on a vast territory of Mozambique and in the eastern regions of Zimbabwe, Botswana, Zambia and SAR ( Fig. 3). In accordance with the US Geological Service NEIC this earthquake was felt in Mozambique cities - Beira, Inhambane, Maputo, Matola (V); in Zimbabwean cities - Harare, Mutare (IV); in SAR cities - Louis Trichardt and Phalaborwa (IV), Durban and Middelburg (III), Johannesburg and Pretoria (II). |
Figure 3 |
|
| Historical records |
| Within the last hundred years of seismic observations no seismic activity with such intensity has been registered here. From the words of American seismologists this was "unexpected and rather strong earthquake for South African region". Fig.4 presents historical seismic picture of this region in accordance with data from NEIC |
Figure 4 |
|
| Focal mechanism and seismic moment of the earthquake |
| Focal mechanism solutions for this earthquake were obtained from data of National Earthquakes Information Center of the US Geological Service (NEIC) and of Harvard Center, USA (HARVARD), they are shown on fig. 5 - 6 in stereographical projection (lower hemisphere, waves of compression in dark) and in table 2. These solutions are almost identical. The earthquake on February 22, 2006 has happened under the action of prevailing strengths of expansion, oriented to the West-South-West direction. Both nodal planes spread along meridian, one of them lays flat, the other has a steep falling angle, type of the motion along both planes - normal fault. The value of seismic moment Мо in accordance with NEIC makes 1.6* 10** 20 n*m, the value of moment magnitude - Mw = 7.4. In accordance with Harvard the value of seismic moment Мо makes 4.5* 10** 19 n*m, the value of moment magnitude - Mw = 7.0. |
| Table 2 |
| Axes of main strengths |
Nodal planes |
Center |
| T |
P |
N |
NP1 |
NP2 |
| Pl |
Azm |
Pl |
Azm |
Pl |
Azm |
Stk |
Dp |
Slip |
Stk |
Dp |
Slip |
| 36 | 266 | 54 | 95 |
4 | 359 | 333 | 10 | -117 | 180 |
81 | -86 | NEIC | | 22 | 251 | 66 | 95 |
8 | 345 | 326 | 24 | -111 | 168 |
67 | -87 | HARVARD | |
| NEIC - National Earthquakes Information Center of US Geological Service |
| HARVARD - Harvard Geophysical Center (USA) |
Figure 5 | 
Figure 6 |
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